How a supernova somewhere in the Milky Way can disrupt cellphone signals on Earth
When a massive star dies it can explode into a supernova, releasing a burst of gamma radiation that can be detected millions of light-years away and interfere with wireless communications on Earth.
So explains Soebur Razzaque, the director of the Centre for Astro-Particle Physics at the University of Johannesburg, whose team recently published their research predicting gamma-ray burst (GRB) behaviour in the journal Nature Astronomy.
Speaking to MyBroadband, Razzaque said that the radiation from a GRB can ionize the magnetosphere of the Earth.
This produces more free electrons which can absorb electromagnetic waves in the radio frequency, disrupting mobile phone networks.
One example of such a gamma-ray burst disrupting communications on Earth occurred on 27 December 2004.
“That event took place on a neutron star or magnetar in our own Milky Way galaxy,” said Razzaque.
However, unlike coronal mass ejections which can knock out electronics, communications networks, and take down power grids, gamma-ray bursts are much less destructive as the supernovas that cause them are much further away than our own sun.
According to Razzaque the duration of disruptions due to GRBs is short — a second or less.
Predicting gamma-ray bursts
In 2005, Razzaque published research based on a GRB event that happened during the previous year and which originated from a rare, powerful neutron star called a magnetar.
Razzaque predicted that there would be a second explosion from the giant flare given off by the neutron star.
Fifteen years later, Razzaque led a team of researchers that collected data from that second explosion.
Dubbed GRB 200415A, the second gamma-ray burst occurred on 15 April 2020 and lasted 140 milliseconds.
This is the first time a second GRB of such a magnetar burst was detected. More exciting is that the data matched the model Razzaque and others developed back in 2005.
The team published their findings in Nature Astronomy in January 2021.
“No two gamma-ray bursts are ever the same, even if they happen in a similar way,” Razzaque said.
“We’re still trying to understand how stars end their life and how these very energetic gamma rays are produced.”
Disruptive gamma rays will come from inside the Milky Way
While the gamma rays given off by GRB 200415A were powerful, the magnetar that emitted the rays was also very far away — about 11 million light-years away.
Razzaque explained that supernovas that can disrupt wireless communications on Earth must come from stars that are much closer, at least from inside our own Milky Way galaxy.
For example, the disruptive burst of gamma rays that hit the Earth on 27 December 2004 came from a star that was only 50 thousand light-years away.
Asked whether such GRBs could harm life on Earth, Razzaque said that the known magnetars in the Milky Way are quite far away.
“The possibility of such an event to cause physical harm to life on earth is extremely low.”
MeerKAT could help study gamma-ray bursts
Razzaque said that if the next giant flare GRB happens closer to our home galaxy the Milky Way, a powerful radio telescope such as South Africa’s MeerKAT may be able to detect it.
“That would be an excellent opportunity to study the relationship between very high energy gamma-ray emissions and radio wave emissions in the second explosion,” he stated.
While the initial gamma-ray burst is short, lasting only fractions of a second, Razzaque explained that past observations show that the radio frequency emissions that follow a GRB lasted for several days.
“It will be possible for MeerKAT to point their radio antennas to the right direction in the sky after alerted by gamma-ray detection. The earlier they can slew and observe, the better,” said Razzaque.
He said that the better we understand these fleeting explosions, the better we may understand the universe we live in.
“We can detect gamma-ray bursts going back to when the universe was a few hundred million years old,” said Razzaque.
“That is at an extremely early stage of the evolution of the universe. The stars that died at that time… we are only detecting their gamma-ray bursts now because light takes time to travel.”
Razzaque said that this means gamma-ray bursts can tell us more about how the universe expands and evolves over time.